Ho to start the sitl simulation for fixed wing and quard copter

HI
am new user of ardupilot software. how to use sitl simulation software . how to download sitl . what is procedure and steps . when am downloading sitl sofware its always faied . please any body help me .

Well… a good place to start is to read the docs

http://ardupilot.org/dev/docs/sitl-simulator-software-in-the-loop.html

or

search a little

This sital is working with wifi network or telemetry link